Metallic material for electronic components and method for producing same, and connector terminals, connectors and electronic components using same

ABSTRACT

The present invention provides metallic materials for electronic components, having low degree of whisker formation, low adhesive wear property and high durability, and connector terminals, connectors and electronic components using such metallic materials. The metallic material for electronic components includes: a base material; a lower layer formed on the base material, the lower layer being constituted with one or two or more selected from a constituent element group A, namely, the group consisting of Ni, Cr, Mn, Fe, Co and Cu; an intermediate layer formed on the lower layer, the intermediate layer being constituted with one or two or more selected from a constituent element group B, namely, the group consisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir; and an upper layer formed on the intermediate layer, the upper layer being constituted with an alloy composed of one or two or more selected from the constituent element group B, namely, the group consisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir and one or two selected from a constituent element group C, namely, the group consisting of Sn and In; wherein the thickness of the lower layer is 0.05 μm or more and less than 5.00 μm; the thickness of the intermediate layer is 0.01 μm or more and less than 0.50 μm; and the thickness of the upper layer is 0.02 μm or more and less than 0.80 μm.

TECHNICAL FIELD

The present invention relates to a metallic material for electroniccomponents and a method for producing the same, and connector terminals,connectors and electronic components using the same.

BACKGROUND ART

In connectors as connecting components for electronic devices forconsumer use and for vehicle use, materials are used in which baseplating of Ni or Cu is applied to the surface of brass or phosphorbronze materials and Sn or Sn alloy plating is further applied to thebase plating. Sn or Sn alloy plating is generally required to haveproperties such as low contact resistance and high solder wettability,and further, recently the reduction of the insertion force has also beenrequired at the time of joining together a male terminal and a femaleterminal molded by press processing of plating materials. In theproduction process, on the plating surface, there occur sometimeswhiskers, which are needle crystals, causing problems such as shortcircuiting, and hence such whiskers are also required to be suppressedsatisfactorily.

In this regard, Patent Literature 1 discloses an electrical contactmaterial including a contact base material, a ground layer composed ofNi or Co, or an alloy of both of Co and Ni and formed on the surface ofthe contact base material, and an Ag—Sn alloy layer formed on thesurface of the ground layer, wherein the average concentration of Sn inthe Ag—Sn alloy layer is less than 10 mass %, and the concentration ofSn in the Ag—Sn alloy layer is varied with a concentration gradient soas to increase from the interface with the ground layer toward thesurface layer portion of the Ag—Sn alloy layer. According to PatentLiterature 1, an electrical contact material excellent in wearresistance, corrosion resistance and processability is described, andthe electrical contact material is described to be able to be producedwith an extremely low cost.

Patent Literature 2 discloses a material for electric/electroniccomponents wherein on the surface of a substrate having a surfacecomposed of Cu or a Cu alloy, through the intermediary of anintermediate layer composed of a Ni layer or a Ni alloy layer, a surfacelayer composed of a Sn layer or a Sn alloy layer is formed, each ofthese layers containing an Ag₃Sn (ε phase) compound and having athickness of 0.5 to 20 μm. As described in Patent Literature 2, anobject of the invention described in Patent Literature 2 is to provide amaterial for electrical/electronic components, wherein the surface layeris lower in melting point than Sn, excellent in solderability, and freefrom the occurrence of whisker; the joint strength of the junctionformed after soldering is high and at the same time the temporaldegradation of the joint strength at high temperatures is hardly caused,and hence the material is suitable for a lead material; even when thematerial is used in a high-temperature environment, the increase of thecontact resistance is suppressed, the material does not cause thedegradation of the connection reliability with the counterpart member,and hence the material is suitable as a contact material, the objectalso including the provision of a method for producing theabove-described material, and the provision of electrical/electroniccomponents using the above-described material.

Patent Literature 3 discloses a covering material including a basematerial having electrically conductive property and a covering layerformed on the base material, wherein the covering layer includes anintermetallic compound of Sn and a precious metal at least on thesurface side thereof. Patent Literature 3 describes an object thereof isto provide a covering material being low in contact resistance, having alow friction coefficient so as to be effective in reduction of insertionforce, being excellent in oxidation resistance and having stableproperties over a long period of time, and a method for producing thecovering material.

CITATION LIST Patent Literature

[Patent Literature 1] Japanese Patent Laid-Open No. Hei 4-370613

[Patent Literature 2] Japanese Patent Laid-Open No. Hei 11-350189

[Patent Literature 3] Japanese Patent Laid-Open No. 2005-126763

SUMMARY OF INVENTION Technical Problem

However, the technique described in Patent Literature 1 has not revealedthe relation to the recently required reduction of the insertion forceand the relation to the occurrence and nonoccurrence of the whiskers.The average concentration of Sn in the Ag—Sn alloy layer is less than 10mass %, and the proportion of Ag in the Ag—Sn alloy layer isconsiderably large, and hence the gas corrosion resistance against thegases such as chlorine gas, sulfurous acid gas and hydrogen sulfide isnot sufficient according to the evaluation performed by the presentinventors.

In the technique described in Patent Literature 2, a surface layer isinvolved which is formed of a Sn layer or a Sn-alloy layer including anAg₃Sn (s-phase) compound and having a thickness of 0.5 to 20 μm, andaccording to the evaluation performed by the present inventors, thissurface layer thickness has resulted in the occurrence of areasincapable of sufficiently reducing the insertion force. The content ofthe Ag₃Sn (s-phase) of the surface layer formed of a Sn layer or aSn-alloy layer is also described to be 0.5 to 5% by mass in terms of Ag,the proportion of Sn in the surface layer formed of a Sn layer or aSn-alloy layer is large, the thickness of the surface layer formed of aSn layer or a Sn-alloy layer, and hence, according to the evaluationperformed by the present inventors, whiskers occurred and the finesliding wear resistance was not sufficient. The heat resistance and thesolder wettability were also not sufficient.

In the technique described in Patent Literature 3, the covering layerincludes an intermetallic compound of Sn and a precious metal, thethickness of the intermetallic compound (Ag₃Sn) of Sn and a preciousmetal is preferably set at 1 μm or more and 3 μm or less. According tothe evaluation performed by the present inventors, this thickness wasfound to be unable to sufficiently decrease the insertion force.

As described above, electronic component metallic materials having aconventional Sn—Ag alloy/Ni base plating structure still cannotsufficiently decrease the insertion force and a problem has been leftunsolved in that whiskers occur. For the durability (heat resistance,solder wettability, fine sliding wear resistance and gas corrosionresistance), it is difficult to achieve sufficiently satisfactoryspecifications and such specifications have not yet been clear.

The present invention has been achieved in order to solve theabove-described problems, and an object of the present invention is toprovide metallic materials for electronic components, having low degreeof whisker formation, low adhesive wear property and high durability,and connector terminals, connectors and electronic components using suchmetallic materials. Here, the adhesive wear means the wear phenomenonmade to occur due to the shear, caused by frictional movement, of theadhesive portions constituting the real contact area between solidobjects. With the increase of the adhesive wear, the insertion force isincreased when a male terminal and a female terminal are joinedtogether.

Solution to Problem

The present inventors made a diligent study, and consequently havediscovered that a metallic material for electronic components, havinglow degree of whisker formation, low adhesive wear property and highdurability can be prepared by disposing a lower layer, an intermediatelayer and an upper layer on a base material, using predetermined metalsfor the lower layer, the intermediate layer and the upper layer,respectively, and assigning predetermined thickness values andpredetermined compositions to the lower, intermediate and upper layers,respectively.

An aspect of the present invention perfected on the basis of theabove-described discovery is a metallic material for electroniccomponents having low degree of whisker formation, low adhesive wearproperty and high durability, the metallic material for electroniccomponents comprising: a base material; a lower layer formed on the basematerial, the lower layer being constituted with one or two or moreselected from a constituent element group A, namely, the groupconsisting of Ni, Cr, Mn, Fe, Co and Cu; an intermediate layer formed onthe lower layer, the intermediate layer being constituted with one ortwo or more selected from a constituent element group B, namely, thegroup consisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir; and an upperlayer formed on the intermediate layer, the upper layer beingconstituted with an alloy composed of one or two or more selected fromthe constituent element group B, namely, the group consisting of Ag, Au,Pt, Pd, Ru, Rh, Os and Ir and one or two selected from a constituentelement group C, namely, the group consisting of Sn and In; wherein thethickness of the lower layer is 0.05 μm or more and less than 5.00 μm;the thickness of the intermediate layer is 0.01 μm or more and less than0.50 μm; the thickness of the upper layer is 0.02 μm or more and lessthan 0.80 μm.

In the metallic material for electronic components of the presentinvention in an embodiment, the minimum thickness (μm) of the upperlayer is 50% or more of the thickness (μm) of the upper layer.

In the metallic material for electronic components of the presentinvention in another embodiment, the maximum value (μm) of the elevationdifferences between the adjacent hills and valleys in the profile of theinterface between the upper layer and the intermediate layer is 50% orless of the thickness (μm) of the upper layer.

In the metallic material for electronic components of the presentinvention in yet another embodiment, on the surface of the upper layer,a region where the total atomic concentration (at %) of the constituentelements C≥2 the total atomic concentration (at %) of the constituentelements B and the atomic concentration (at %) of O≥10 at % is presentin the range of 0.02 μm or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the upper layer includes themetal(s) of the constituent element group C in a content of 10 to 50 at%.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, a ζ(zeta)-phasebeing a Sn—Ag alloy including Sn in a content of 11.8 to 22.9 at % ispresent.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, anε(epsilon)-phase being Ag₃Sn is present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, a ζ(zeta)-phasebeing a Sn—Ag alloy including Sn in a content of 11.8 to 22.9 at % andan ε(epsilon)-phase being Ag₃Sn are present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, only theε(epsilon)-phase being Ag₃Sn is present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, theε(epsilon)-phase being Ag₃Sn and 3-Sn being a Sn single phase arepresent.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the upper layer, theζ(zeta)-phase being a Sn—Ag alloy including Sn in a content of 11.8 to22.9 at %, the ε(epsilon)-phase being Ag₃Sn and n-Sn being a Sn singlephase are present.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the thickness of the upper layer isless than 0.50 μm.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the thickness of the intermediatelayer is 0.05 μm or more and less than 0.30 μm.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the thickness ratio between theupper layer and the intermediate layer is such that upperlayer:intermediate layer=1:9 to 9:1.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the range from the upper layerto the intermediate layer, exclusive of the range of 0.03 μm from theoutermost surface of the upper layer, C, S and O are each included in acontent of 2 at % or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the indentation hardness of thesurface of the upper layer, namely, the hardness obtained by hitting adent on the surface of the upper layer with a load of 10 mN on the basisof a nanoindentation hardness test is 1000 MPa or more.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the indentation hardness measuredfrom the surface of the upper layer, namely, the hardness obtained byhitting a dent on the surface of the upper layer with a load of 10 mN onthe basis of a nanoindentation hardness test is 10000 MPa or less.

In the metallic material for electronic components of the presentinvention, in yet another embodiment thereof, the arithmetic mean height(Ra) of the surface of the upper layer is 0.3 μm or less.

In the metallic material for electronic components of the presentinvention, in yet another embodiment thereof, the maximum height (Rz) ofthe surface of the upper layer is 3 μm or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the upper layer, the intermediatelayer and the lower layer are formed, by forming a film of one or two ormore selected from the constituent element group A on the base material,then forming a film of one or two selected from the constituent elementgroup B, then forming a film of one or two or more selected from theconstituent element group C, and by diffusion of the respective selectedelements of the constituent element group B and the constituent elementgroup C.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the diffusion is performed by heattreatment.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the heat treatment is performed ata temperature equal to higher than the melting point(s) of the metal(s)of the constituent element group C, an alloy layer of one or two or moreselected from the constituent element group B and one or two selectedfrom the constituent element group C are formed.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the content of the metal(s) of theconstituent element group A is 50% by mass or more in terms of the totalcontent of Ni, Cr, Mn, Fe, Co and Cu, and one or two or more selectedfrom the group consisting of B, P, Sn and Zn are further included.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the content of the metal(s) of theconstituent element group B is 50% by mass or more in terms of the totalcontent of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir, and the rest alloycomponent is composed of one or two or more selected from the groupconsisting of Bi, Cd, Co, Cu, Fe, In, Mn, Mo, Ni, Pb, Sb, Se, Sn, W, Tland Zn.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the content of the metal(s) of theconstituent element group C is 50% by mass or more in terms of the totalcontent of Sn and In, and the rest alloy component is composed of one ortwo or more selected from the group consisting of Ag, As, Au, Bi, Cd,Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, W and Zn.

In the metallic material for electronic components of the presentinvention, in yet another embodiment thereof, the Vickers hardness ofthe cross section of the lower layer is Hv 300 or more.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the indentation hardness of thecross section of the lower layer, namely, the hardness obtained byhitting a dent on the cross section of the lower layer with a load of 10mN on the basis of a nanoindentation hardness test is 1500 MPa or more.

In the metallic material for electronic components of the presentinvention, in yet another embodiment thereof, the Vickers hardness ofthe cross section of the lower layer is Hv 1000 or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, the indentation hardness of thecross section of the lower layer, namely, the hardness obtained byhitting a dent on the cross section of the lower layer with a load of 10mN on the basis of a nanoindentation hardness test is 10000 MPa or less.

In the metallic material for electronic components of the presentinvention in yet another embodiment, P is deposited on the surface ofthe upper layer, and the deposition amount of P is 1×10¹¹ to 4×10⁻⁸mol/cm².

In the metallic material for electronic components of the presentinvention in yet another embodiment, N is further deposited on thesurface of the upper layer, and the deposition amount of N is 2×10⁻¹² to8×10⁻⁹ mol/cm².

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the XPS analysis performed forthe upper layer, with I(P2s) denoting the photoelectron detectionintensity due to the 2S orbital electron of P to be detected and I(N1s)denoting the photoelectron detection intensity due to the 1S orbitalelectron of N to be detected, the relation 0.1≤I(P2s)/I(N1s)≤1 issatisfied.

In the metallic material for electronic components of the presentinvention in yet another embodiment, in the XPS analysis performed forthe upper layer, with I(P2s) denoting the photoelectron detectionintensity due to the 2S orbital electron of P to be detected and I(N1s)denoting the photoelectron detection intensity due to the 1S orbitalelectron of N to be detected, the relation 1≤I(P2s)/I(N1s)≤50 issatisfied.

Another aspect of the present invention is a method for producing themetallic material for electronic components, the metallic materialcomprising: a base material; a lower layer formed on the base material,the lower layer being constituted with one or two or more selected froma constituent element group A, namely, the group consisting of Ni, Cr,Mn, Fe, Co and Cu; an intermediate layer formed on the lower layer, theintermediate layer being constituted with one or two or more selectedfrom a constituent element group B, namely, the group consisting of Ag,Au, Pt, Pd, Ru, Rh, Os and Ir; and an upper layer formed on theintermediate layer, the upper layer being constituted with an alloycomposed of one or two or more selected from the constituent elementgroup B, namely, the group consisting of Ag, Au, Pt, Pd, Ru, Rh, Os andIr and one or two selected from a constituent element group C, namely,the group consisting of Sn and In, wherein the surface of the metallicmaterial is surface-treated with a phosphoric acid ester-based solutionincluding at least one of the phosphoric acid esters represented by thefollowing general formulas [1] and [2], and at least one selected fromthe group of the cyclic organic compounds represented by the followinggeneral formulas [3] and [4]:

(wherein, in formulas [1] and [2], R₁ and R₂ each represent asubstituted alkyl group and M represents a hydrogen atom or an alkalimetal atom,)

(wherein, in formulas [3] and [4], R₁ represents a hydrogen atom, analkyl group or a substituted alkyl group; R₂ represents an alkali metalatom, a hydrogen atom, an alkyl group or a substituted alkyl group; R₃represents an alkali metal atom or a hydrogen atom; R₄ represents —SH,an alkyl group-substituted or aryl group-substituted amino group, orrepresents an alkyl-substituted imidazolylalkyl group; and R₅ and R₆each represent —NH₂, —SH or —SM (M represents an alkali metal atom).)

In the method for producing metallic material for electronic componentsof the present invention in an embodiment, the surface treatment withthe phosphoric acid ester-based solution is performed by applying thephosphoric acid ester-based solution to the upper layer.

In the method for producing metallic material for electronic componentsof the present invention in another embodiment, the surface treatmentwith the phosphoric acid ester-based solution is performed by conductingan electrolysis by immersing the metallic material after the formationof the upper layer in the phosphoric acid ester-based solution and usingas the anode the metallic material after the formation of the upperlayer.

The present invention is, in yet another aspect thereof, a connectorterminal using, in the contact portion thereof, the metallic materialfor electronic components of the present invention.

The present invention is, in yet another aspect thereof, a connectorusing the connector terminal of the present invention.

The present invention is, in yet another aspect thereof, an FFC terminalusing, in the contact portion thereof, the metallic material forelectronic components of the present invention.

The present invention is, in yet another aspect thereof, an FPC terminalusing, in the contact portion thereof, the metallic material forelectronic components of the present invention.

The present invention is, in yet another aspect thereof, an FFC usingthe FFC terminal of the present invention.

The present invention is, in yet another aspect thereof, an FPC usingthe FPC terminal of the present invention.

The present invention is, in yet another aspect thereof, an electroniccomponent using, in the electrode thereof for external connection, themetallic material for electronic components of the present invention.

The present invention is, in yet another aspect thereof, an electroniccomponent using the metallic material for electronic components of thepresent invention, in a push-in type terminal thereof for fixing a boardconnection portion to a board by pushing the board connection portioninto the through hole formed in the board, wherein a female terminalconnection portion and the board connection portion are providedrespectively on one side and the other side of a mounting portion to beattached to a housing.

Advantageous Effects of Invention

According to the present invention, it is possible to provide metallicmaterials for electronic components, having low degree of whiskerformation, low adhesive wear property and high durability, and connectorterminals, connectors and electronic components using such metallicmaterials.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating the structure of a metallicmaterial for electronic components according to an embodiment of thepresent invention.

FIG. 2 is an XPS analysis chart of a metallic material for electroniccomponents according to the present invention.

FIG. 3 is a graph showing the relation between the deposition amountsand the detection intensities of the components of the post treatmentsolution of a metallic material for electronic components according tothe present invention.

FIG. 4 is a schematic diagram of the HAADF(High-Angle-Annular-Dark-Filed)-STEM (scanning transmission electronmicroscope) image of a metallic material for electronic componentsaccording to the present invention.

FIG. 5 is a schematic diagram of the STEM (scanning transmissionelectron microscope) line analysis results of a metallic material forelectronic components according to the present invention.

FIG. 6 is the phase diagram of Sn—Ag.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the metallic materials for electronic components accordingto the embodiments of the present invention are described. As shown inFIG. 1, the metallic material 10 for electronic components according toan embodiment includes a base material 11, an lower layer 12 formed onthe base material 11, an intermediate layer 13 formed on the lower layer12 and an upper layer 14 formed on the intermediate layer 13.

<Structure of Metallic Material for Electronic Components>

(Base Material)

Usable examples of the base material 11 include, without beingparticularly limited to: metal base materials such as copper and copperalloys, Fe-based materials, stainless steel, titanium and titaniumalloys and aluminum and aluminum alloys. The base material 11 may beformed by combining a metal base material with a resin layer. Examplesof the base material formed by combining a metal base material with aresin layer include the electrode portions in FPC and FFC basematerials.

(Upper Layer)

The upper layer 14 is required to be constituted with an alloy composedof one or two selected from a constituent element group B, namely, thegroup consisting of Sn and In, and one or two or more selected from aconstituent element group C, namely, the group consisting of Ag, Au, Pt,Pd, Ru, Rh, Os and Ir.

Sn and In are oxidizable metals, but are characterized by beingrelatively soft among metals. Accordingly, even when an oxide film isformed on the surface of Sn or In, for example at the time of joiningtogether a male terminal and a female terminal by using a metallicmaterial for electronic components as a contact material, the oxide filmis easily scraped to result in contact between metals, and hence a lowcontact resistance is obtained.

Sn and In are excellent in the gas corrosion resistance against thegases such as chlorine gas, sulfurous acid gas and hydrogen sulfide gas;for example, when Ag poor in gas corrosion resistance is used for theupper layer 14, Ni poor in gas corrosion resistance is used for thelower layer 12, and copper or a copper alloy poor in gas corrosionresistance is used for the base material 11, Sn and In have an effect toimprove the gas corrosion resistance of the metallic material forelectronic components. As for Sn and In, Sn is preferable because In isseverely regulated on the basis of the technical guidelines for theprevention of health impairment prescribed by the Ordinance of Ministryof Health, Labour and Welfare.

Ag, Au, Pt, Pd, Ru, Rh, Os and Ir are characterized by being relativelyheat-resistant among metals. Accordingly, these metals suppress thediffusion of the composition of the base material 11 and the lower layer12 toward the side of the upper layer 14 to improve the heat resistance.These metals also form compounds with Sn or In in the upper layer 14 tosuppress the formation of the oxide film of Sn or In, so as to improvethe solder wettability. Among Ag, Au, Pt, Pd, Ru, Rh, Os and Ir, Ag ismore desirable from the viewpoint of electrical conductivity. Ag is highin electrical conductivity. For example, when Ag is used forhigh-frequency wave signals, impedance resistance is made low due to theskin effect.

The thickness of the upper layer 14 is required to be 0.02 μm or moreand less than 0.80 μm. When the thickness of the upper layer 14 is lessthan 0.02 μm, for example, in the case where the metal of theconstituent element group B is Ag, the gas corrosion resistance is poor,and the exterior appearance is discolored when a gas corrosion test isperformed. On the other hand, when the thickness of the upper layer 14is 0.80 μm or more, the thin film lubrication effect due to the hardbase material 11 or the hard lower layer 12 is degraded and the adhesivewear is increased. The mechanical durability is also degraded andscraping of plating tends to occur. The thickness of the upper layer 14is preferably less than 0.50 μm.

The upper layer 14 preferably includes the metal(s) of the constituentelement group C in a content of 10 to 50 at %. When the content of themetal(s) of the constituent element group C is less than 10 at %, forexample, in the case where the metal of the constituent element group Bis Ag, the gas corrosion resistance is poor, and sometimes the exteriorappearance is discolored when a gas corrosion test is performed. On theother hand, when the content of the metal(s) of the constituent elementgroup C exceeds 50 at %, the proportion of the metal(s) of theconstituent element group C in the upper layer 14 is large, and hencethe adhesive wear is increased and whiskers also tend to occur.Moreover, the fine sliding wear resistance is sometimes poor.

In the upper layer 14, the ζ(zeta)-phase being a Sn—Ag alloy includingSn in a content of 11.8 to 22.9 at % is preferably present. By thepresence of the ζ(zeta)-phase, the gas corrosion resistance is improved,and the exterior appearance is hardly discolored even when the gascorrosion test is performed.

In the upper layer 14, the ζ(zeta)-phase and the ε(epsilon)-phase beingAg₃Sn are preferably present. By the presence of the ε(epsilon)-phase,as compared with the case where only the ζ(zeta)-phase is present in theupper layer 14, the coating becomes harder and the adhesive wear isdecreased. The increase of the proportion of Sn in the upper layer 14improves the gas corrosion resistance.

In the upper layer 14, preferably only the ε(epsilon)-phase being Ag₃Snis present. By the sole presence of the ε(epsilon)-phase in the upperlayer 14, the coating becomes further harder and the adhesive wear isdecreased as compared with the case where the ζ(zeta)-phase and theε(epsilon)-phase being Ag₃Sn are present in the upper layer 14. The moreincrease of the proportion of Sn in the upper layer 14 also improves thegas corrosion resistance.

The presence of the ε(epsilon)-phase being Ag₃Sn and the n-Sn being a Snsingle phase in the upper layer 14 is preferable. By the presence of theε(epsilon)-phase being Ag₃Sn and n-Sn being a Sn single phase, the gascorrosion resistance is improved with a further increase of theproportion of Sn in the upper layer as compared with the case where onlythe ε(epsilon)-phase is present in the upper layer 14.

In the upper layer 14, preferably the ζ(zeta)-phase being a Sn—Ag alloyincluding Sn in a content of 11.8 to 22.9 at %, the ε(epsilon)-phasebeing Ag₃Sn and n-Sn being a Sn single phase are present. By thepresence of the ζ(zeta)-phase, the ε(epsilon)-phase being Ag₃Sn and n-Snbeing a Sn single phase, the gas corrosion resistance is improved, theexterior appearance is hardly discolored even when a gas corrosion testis performed, and the adhesive wear is decreased. The constitutionconcerned is created by a diffusion process and involves no structure inan equilibrium state.

The upper layer 14 should not be present as solely composed of 3-Sn.When the upper layer 14 is present as solely composed of 3-Sn, theadhesive wear is significant, whiskers occur and, for example, the heatresistance and the fine sliding wear resistance are degraded.

(Intermediate Layer)

The intermediate layer 13 is required to be constituted with one or twoor more selected from the constituent element group B, namely, the groupconsisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir.

The intermediate layer 13 is constituted with one or two or moreselected from the constituent element group B, namely, the groupconsisting of Ag, Au, Pt, Pd, Ru, Rh, Os and Ir, and hence theintermediate layer offers an effect to improve heat resistance or solderwettability. Among Ag, Au, Pt, Pd, Ru, Rh, Os and Ir, Ag is moredesirable from the viewpoint of electrical conductivity. Ag is high inelectrical conductivity. For example, when Ag is used for high-frequencywave signals, impedance resistance is made low due to the skin effect.

The thickness of the intermediate layer 13 is required to be 0.01 μm ormore and less than 0.50 μm. When the thickness of the intermediate 13 isless than 0.01 μm, the composition of the base material 11 or the lowerlayer 12 tends to diffuse to the side of the upper layer 14 and the heatresistance or the solder wettability is degraded. Additionally, theupper layer 14 is worn by fine sliding, and the lower layer 12 high incontact resistance tends to be exposed, and hence the fine sliding wearresistance is poor and the contact resistance tends to be increased byfine sliding. Moreover, the lower layer 12 poor in gas corrosionresistance tends to be exposed, and hence the gas corrosion resistanceis poor, and the exterior appearance is discolored when a gas corrosiontest is performed. On the other hand, when the thickness of theintermediate layer 13 is 0.50 μm or more, the thin film lubricationeffect due to the hard base material 11 or the hard lower layer 12 isdegraded and the adhesive wear is increased. The mechanical durabilityis also degraded and scraping of plating tends to occur. The thicknessof the intermediate layer 13 is preferably 0.05 μm or more and less than0.30 μm.

(Relation Between Thickness of Upper Layer and Minimum Thickness ofUpper Layer)

The minimum thickness (μm) of the upper layer 14 preferably accounts for50% or more of the thickness (μm) of the upper layer 14. When theminimum thickness of the upper layer 14 is less than 50% of thethickness of the upper layer 14, the surface roughness of the upperlayer 14 is rough, and for example, in the case where the metal of theconstituent element group B is Ag, the gas corrosion resistance is poor,and sometimes the exterior appearance is discolored when a gas corrosiontest is performed.

Here, the spot for grasping the relation between the thickness of theupper layer 14 and the minimum thickness of the upper layer 14 is theaverage cross section of the portion exhibiting the effect of thecoating of the present invention. The spot refers to the portionnormally subjected to film formation processing in the normal surfaceprofile (oil pits, etch pits, scratches, dents, and other surfacedefects are not included) of the material, in the portion concerned.Needless to say, the spot excludes the deformed portions or the like dueto the press processing before and after the film formation.

(Relation Between Thickness of Upper Layer and Maximum Value ofElevation Differences Between Adjacent Hills and Valleys in Profile ofInterface Between Upper Layer and Intermediate Layer)

The maximum value (μm) of the elevation differences between the adjacenthills and valleys in the profile of the interface between the upperlayer 14 and the intermediate layer 13 preferably accounts for 50% orless of the thickness (μm) of the upper layer 14. When the maximum value(μm) of the elevation differences between the adjacent hills and valleysin the profile of the interface between the upper layer 14 and theintermediate layer 13 exceeds 50% of the thickness of the upper layer14, the intermediate layer 13 is to be positioned near the upper layer14, and for example, in the case where the metal of the constituentelement group B is Ag, the gas corrosion resistance is poor, andsometimes the exterior appearance is discolored when a gas corrosiontest is performed.

The microscopic distribution of the thickness of the upper layer 14 andthe profile of the interface between the upper layer 14 and theintermediate layer 13 can be controlled by the film formation conditionsof the lower layer 12, intermediate layer 13 and upper layer 14. At thetime of film formation, by regulating the plating conditions (metalconcentration, additives, cathode current density, stirring and thelike), smooth electrodeposition film formation is performed so as tosatisfy the above-described “relation between the thickness of the upperlayer and the minimum thickness of the upper layer,” and theabove-described “relation between the thickness of the upper layer andthe maximum value of the elevation differences between the adjacenthills and valleys in the profile of the interface between the upperlayer and the intermediate layer.”

(Thickness Ratio Between Upper Layer and Intermediate Layer)

The thickness ratio between the upper layer and the intermediate layerpreferably satisfies the condition of upper layer:intermediate layer=1:9to 9:1. When in the ratio, upper layer:intermediate layer, theproportion of the upper layer is less than “upper layer:intermediatelayer=1:9,” for example, in the case where the metal of the constituentelement group B is Ag, the gas corrosion resistance is poor, andsometimes the exterior appearance is discolored when a gas corrosiontest is performed. On the other hand, when in the ratio, upperlayer:intermediate layer, the proportion of the upper layer is largerthan “upper layer:intermediate layer=9:1,” sometimes the heat resistanceor the solder wettability is poor.

In the range from the upper layer 14 to the intermediate layer 13,exclusive of the range of 0.03 μm from the outermost surface of theupper layer 14, C, S and O are each included preferably in a content of2 at % or less. When the content of each of C, S and O is larger than 2at %, these co-deposited elements are gasified in the application ofheat treatment, and no uniform alloy coating may be able to be formed.

(Lower Layer)

Between the base material 11 and the upper layer 14, it is necessary toform the lower layer 12 constituted with one or two or more selectedfrom the constituent element group A, namely, the group consisting ofNi, Cr, Mn, Fe, Co and Cu. By forming the lower layer 12 with one or twoor more metals selected from the constituent element group A, namely,the group consisting of Ni, Cr, Mn, Fe, Co and Cu, the hard lower layer12 is formed, hence the thin film lubrication effect is improved and theadhesive wear is decreased, and the lower layer 12 prevents thediffusion of the constituent metal(s) of the base material 11 into theupper layer 14 and improves, for example, the heat resistance or thesolder wettability.

The thickness of the lower layer 12 is required to be 0.05 μm or more.When the thickness of the lower layer 12 is less than 0.05 μm, the thinfilm lubrication effect due to the hard lower layer is degraded and theadhesive wear is increased. The diffusion of the constituent metal(s) ofthe base material 11 into the upper layer 14 is facilitated, and theheat resistance or the solder wettability is degraded. On the otherhand, the thickness of the lower layer 12 is required to be less than5.00 μm. When the thickness is 5.00 μm or more, bending processabilityis poor.

On the surface of the upper layer 14, a region where the total atomicconcentration (at %) of the constituent elements C≥2 the total atomicconcentration (at %) of the constituent elements B and the atomicconcentration (at %) of O≥10 at % is preferably present in the range of0.02 μm or less. The constituent elements C such as Sn has affinity withO, and hence the surface is bonded to O after Sn plating. Even when heattreatment is applied, the oxide of Sn formed by this bonding does notundergo Sn—Ag alloying and maintains the state before the heattreatment, the above-described region is present. However, when theregion concerned exceeds the range of 0.02 μm, sometimes the contactresistance or the solder wettability is degraded.

(Constituent Element Group A)

The metal(s) of the constituent element group A includes Ni, Cr, Mn, Fe,Co and Cu in the total amount of these of 50 mass % or more, and mayfurther include one or two or more selected from the group consisting ofB, P, Sn and Zn. The alloy composition of the lower layer 12 having sucha constitution as described above makes the lower layer 12 harder andfurther improves the thin film lubrication effect to further decreasethe adhesive wear; the alloying of the lower layer 12 further preventsthe diffusion of the constituent metals of the base material 11 into theupper layer, and sometimes improves the durability such as the heatresistance and the solder wettability in such a way.

(Constituent Element Group B)

The content of the metal(s) of the constituent element group B is 50% bymass or more in terms of the total content of Ag, Au, Pt, Pd, Ru, Rh, Osand Ir, and the rest alloy component may be composed of one or two ormore selected from the group consisting of Bi, Cd, Co, Cu, Fe, In, Mn,Mo, Ni, Pb, Sb, Se, Sn, W, Tl and Zn. Sometimes, these metals furtherdecreases the adhesive wear, suppresses the occurrence of whisker, andadditionally improves the durability such as the heat resistance or thesolder wettability.

(Constituent Element Group C)

The content of the metal(s) of the constituent element group C is 50% bymass or more in terms of the total content of Sn and In, and the restalloy component may be composed of one or two or more selected from thegroup consisting of Ag, As, Au, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb,Sb, W and Zn. Sometimes, these metals further decreases the adhesivewear, suppresses the occurrence of whisker, and additionally improvesthe durability such as the heat resistance or the solder wettability.

(Diffusion Treatment) The upper layer 14, the intermediate layer 13 andthe lower layer 12 may be formed, by forming a film of one or two ormore selected from the constituent element group A on the base material,then forming a film of one or two selected from the constituent elementgroup B, then forming a film of one or two or more selected from theconstituent element group C, and by diffusion of the respective selectedelements of the constituent element group B and the constituent elementgroup C. For example, when the metal from the constituent element groupB is Ag and the metal from the constituent element group C is Sn, thediffusion of Ag into Sn is fast, and thus a Sn—Ag alloy layer is formedby spontaneous diffusion of Sn. The formation of the alloy layer canfurther reduce the adhesion force of Sn, and the low degree of whiskerformation and the durability can also be further improved.

(Heat Treatment)

After the formation of the upper layer 14, a heat treatment may beapplied for the purpose of further suppressing the adhesive wear andfurther improving the low degree of whisker formation and thedurability. The heat treatment allows the metal(s) of the constituentelement group B and the metal(s) of the constituent element layer C ofthe upper layer to form an alloy layer more easily, further reduces theadhesion force of Sn, and can further improve the low degree of whiskerformation and the durability.

For the heat treatment, the treatment conditions (temperature×time) canbe appropriately selected. The heat treatment is not particularlyrequired to be applied. When the heat treatment is applied, the heattreatment performed at a temperature equal to or higher than the highestmelting point of the metal(s) selected from the constituent elementgroup B allows one or two or more selected from the constituent elementgroup B and one or two selected from the constituent element group C toform an alloy layer more easily.

(Post-Treatment)

To the upper layer 14, or to the upper layer 14 after being subjected toheat treatment, a post-treatment may be applied for the purpose offurther decreasing the adhesive wear and improving the low degree ofwhisker formation and the durability. The post-treatment improves thelubricity, further decreases the adhesive wear, suppress the oxidationof the upper layer 14, and can improve the durability such as the heatresistance or the solder wettability. Specific examples of thepost-treatment include phosphoric acid salt treatment, lubricationtreatment and silane coupling treatment using an inhibitor. For thepost-treatment, the treatment conditions (temperature×time) can beappropriately selected. The post-treatment is not particularly requiredto be applied.

The post-treatment is preferably performed for the surface of the upperlayer 14 by using an aqueous solution (referred to as the phosphoricacid ester-based solution) including one or two or more phosphoric acidesters and one or two or more cyclic organic compounds. The phosphoricacid ester(s) added to the phosphoric acid ester-based solution playsthe functions as an antioxidant for plating and a lubricant for plating.The phosphoric acid esters used in the present invention are representedby the general formula [1] and [2]. Examples of the preferable compoundsamong the compounds represented by the general formula [1] includelauryl acidic phosphoric acid monoester. Examples of the preferablecompounds among the compounds represented by the general formula [2]include lauryl acidic phosphoric acid diester.

(wherein, in formulas [1] and [2], R₁ and R₂ each represent asubstituted alkyl group and M represents a hydrogen atom or an alkalimetal atom.)

The cyclic organic compound added to the phosphoric acid ester-basedsolution plays the function as an antioxidant for plating. The group ofthe cyclic organic compounds used in the present invention arerepresented by the general formula [3] and [4]. Examples of thepreferable compounds among the cyclic organic compounds represented bythe general formulas [3] and [4] include: mercaptobenzothiazole, Na saltof mercaptobenzothiazole, K salt of mercaptobenzothiazole,benzotriazole, 1-methyltriazole, tolyltriazole and triazine-basedcompounds.

(wherein, in formulas [3] and [4], R₁ represents a hydrogen atom, analkyl group or a substituted alkyl group; R₂ represents an alkali metalatom, a hydrogen atom, an alkyl group or a substituted alkyl group; R₃represents an alkali metal atom or a hydrogen atom; R₄ represents —SH,an alkyl group-substituted or aryl group-substituted amino group, orrepresents an alkyl-substituted imidazolylalkyl group; and R₅ and R₆each represent —NH₂, —SH or —SM (M represents an alkali metal atom).)

The post-treatment is furthermore preferably performed in such a waythat both P and N are present on the surface of the upper layer 14. WhenP is absent on the plating surface, the solderability tends to bedegraded, and the lubricity of the plating material is also degraded. Onthe other hand, when N is absent on the Sn or Sn alloy plating surface,sometimes the contact resistance of the plating material tends to beincreased in a high temperature environment.

Moreover, in the present invention, in the case where P is deposited onthe surface of the upper layer 14, when the deposition amount of P is1×10⁻¹¹ to 4×10⁻⁸ mol/cm², preferably the solderability is hardlydegraded, the lubricity is satisfactory and the increase of the contactresistance is also reduced. In the case where N is additionallydeposited on the surface of the upper layer 14, more preferably thedeposition amount of N is 2×10⁻¹² to 8×10⁻⁹ mol/cm². When the depositionamount of P is less than 1×10⁻¹¹ mol/cm², the solder wettability tendsto be degraded, and when the deposition amount of P exceeds 4×10⁻⁸mol/cm², sometimes the failure of the increase of the contact resistanceoccurs.

When in the XPS analysis performed for the upper layer 14, with I(P2s)denoting the photoelectron detection intensity due to the 2S orbitalelectron of P to be detected and I(N1s) denoting the photoelectrondetection intensity due to the 1S orbital electron of N to be detected,the relation 0.1≤I(P2s)/I(N1s)≤1 is satisfied, sometimes the contactresistance and the solderability of the plating material is hardlydegraded in a high temperature environment. When the value ofI(P2s)/I(N1s) is less than 0.1, for example, the function to prevent thecontact resistance degradation is not sufficient, and when the value ofI(P2s)/I(N1s) exceeds 1, the contact resistance at the early stage comesto be slightly high, but, as described below, sometimes the dynamicfriction coefficient of the plating material comes to be small. In thiscase, I(P2s) and I(N1s) more preferably satisfy the relation0.3≤I(P2s)/I(N1s)≤0.8.

When in the XPS analysis performed, in the same manner as describedabove, for the upper layer 14, with I(P2s) denoting the photoelectrondetection intensity due to the 2S orbital electron of P to be detectedand I(N1s) denoting the photoelectron detection intensity due to the 1Sorbital electron of N to be detected, the relation 1≤I(P2s)/I(N1s)≤50 issatisfied, sometimes the dynamic friction coefficient of the platingmaterial comes to be small and the insertion force of terminals andconnectors comes to be low. When the value of I(P2s)/I(N1s) is 1 orless, the insertion force comes to be slightly high, and when the valueof I(P2s)/I(N1s) exceeds 50, the insertion force comes to be low, butsometimes the contact resistance at the early stage comes to be high andthe solderability at the early stage is also degraded. In this case,I(P2s) and I(N1s) more preferably satisfy the relation5<I(P2s)/I(N1s)≤40.

The concentration of the phosphoric acid ester(s) for obtaining thedeposition amounts of the post-treatment solution components on thesurface of the upper layer 14 of the present invention is 0.1 to 10 g/L,and preferably 0.5 to 5 g/L. On the other hand, the concentration of thecyclic organic compound(s) is, in relation to the total volume of thetreatment solution, 0.01 to 1.0 g/L and preferably 0.05 to 0.6 g/L.

The phosphoric acid ester-based solution is an aqueous solution havingthe above-described components, and when the solution is heated toincrease the temperature of the solution to 40 to 80° C., theemulsification of the components into water proceed faster, and thedrying of the materials after the treatment is facilitated.

The surface treatment may also be performed by applying the phosphoricacid ester-based solution to the surface of the upper layer 14 after theformation of the upper layer 14. Examples of the method for applying thesolution concerned include: spray coating, flow coating, dip coating androll coating; from the viewpoint of productivity, dip coating or spraycoating is preferable. On the other hand, as another treatment method,the surface treatment with the phosphoric acid ester-based solution mayalso be performed by conducting an electrolysis by immersing themetallic material after the formation of the upper layer 14 in thephosphoric acid ester-based solution and using as the anode the metallicmaterial after the formation of the upper layer 14. The metallicmaterial subjected to the treatment based on this method offers anadvantage that the contact resistance in a high temperature environmentis more hardly increased.

The hitherto presented description of the surface treatment with thephosphoric acid ester-based solution may be performed either after theformation of the upper layer 14 or after the reflow treatment subsequentto the formation of the upper layer 14. The surface treatment is notparticularly temporarily limited, but from industrial viewpoint, thesurface treatment is preferably performed as a sequence of steps.

<Properties of Metallic Material for Electronic Components>

The indentation hardness of the surface of the upper layer 14, namely,the hardness obtained by hitting a dent on the surface of the upperlayer 14 with a load of 10 mN on the basis of a nanoindentation hardnesstest is preferably 1000 MPa or more. The indentation hardness being 1000MPa or more improves the thin film lubrication effect due to the hardupper layer 14, and decreases the adhesive wear. The indentationhardness of the surface of the upper layer 14 is preferably 10000 MPa orless. The indentation hardness of the surface of the upper layer 14being 10000 MPa improves the bending processability, makes cracks hardlyoccur in the molded portion when the metallic material for electroniccomponents of the present invention is subjected to press molding, andconsequently suppresses the degradation of the gas corrosion resistance.

The arithmetic mean height (Ra) of the surface of the upper layer 14 ispreferably 0.3 μm or less. The arithmetic mean height (Ra) of thesurface of the upper layer 14 being 0.3 μm or less reduces the raisedportions of the surface relatively tending to be corroded, thus smoothesthe surface and improves the gas corrosion resistance.

The maximum height (Rz) of the surface of the upper layer 14 ispreferably 3 μm or less. The maximum height (Rz) of the surface of theupper layer 14 being 3 μm or less reduces the raised portions relativelytending to be corroded, thus smoothes the surface and improves the gascorrosion resistance.

The Vickers hardness of the cross section of the lower layer 12 ispreferably Hv 300 or more. The Vickers hardness of the cross section ofthe lower layer 12 being Hv 300 or more makes the lower layer 12 harderand further improves the thin film lubrication effect to furtherdecrease the adhesive wear. On the other hand, the Vickers hardnessHv1000 of the cross section of the lower layer 12 is preferably Hv 1000or less. The Vickers hardness of the cross section of the lower layer 12being Hv 1000 or less improves the bending processability, makes crackshardly occur in the molded portion when the metallic material forelectronic components of the present invention is subjected to pressmolding, and consequently suppresses the degradation of the gascorrosion resistance.

The indentation hardness of the cross section of the lower layer 12 ispreferably 1500 MPa or more. The indentation hardness of the crosssection of the lower layer 12 being 1500 MPa or more makes the lowerlayer harder and further improves the thin film lubrication effect anddecreases the adhesive wear. On the other hand, the indentation hardnessof the cross section of the lower layer 12 is preferably 10000 MPa orless. The indentation hardness of the cross section of the lower layer12 being 10000 MPa or less improves the bending processability, makescracks hardly occur in the molded portion when the metallic material forelectronic components of the present invention is subjected to pressmolding, and consequently suppresses the degradation of the gascorrosion resistance.

<Applications of Metallic Material for Electronic Components>

Examples of the application of the metallic material for electroniccomponents of the present invention include, without being particularlylimited to: a connector terminal using, in the contact portion thereof,the metallic material for electronic components, an FFC terminal or anFPC terminal using, in the contact portion thereof, the metallicmaterial for electronic components, and an electronic component using,in the electrode thereof for external connection, the metallic materialfor electronic components. The terminal does not depend on theconnection mode on the wiring side as exemplified by a crimp-typeterminal, a soldering terminal and a press-fit terminal. Examples of theelectrode for external connection include a connection componentprepared by applying a surface treatment to a tab, and material surfacetreated for use in under bump metal of a semiconductor.

Connectors may also be prepared by using such connector terminals formedas described above, and an FFC or an FPC may also be prepared by usingan FFC terminal or an FPC terminal.

The metallic material for electronic components of the present inventionmay also be used in a push-in type terminal for fixing a boardconnection portion to a board by pushing the board connection portioninto the through hole formed in the board, wherein a female terminalconnection portion and the board connection portion are providedrespectively on one side and the other side of a mounting portion to beattached to a housing.

In a connector, both of the male terminal and the female terminal may bemade of the metallic material for electronic components of the presentinvention, or only one of the male terminal and the female terminal maybe made of the metallic material for electronic components of thepresent invention. The use of the metallic material for electroniccomponents of the present invention for both of the male terminal andthe female terminal further improves the low degree ofinsertion/extraction force.

<Method for Producing Metallic Material for Electronic Components>

As the method for producing the metallic material for electroniccomponents of the present invention, for example, either a wet plating(electroplating or electroless plating) or a dry plating (sputtering orion plating) can be used.

EXAMPLES

Hereinafter, Examples of the present invention, Reference Examples andComparative Examples are presented together; these Examples andComparative Examples are provided for better understanding of thepresent invention, and are not intended to limit the present invention.

As Examples, Reference Examples and Comparative Examples, under theconditions shown in Table 1, the surface treatment was performed in thesequence of electrolytic degreasing, acid cleaning, first plating,second plating, third plating and heat treatment.

(Materials)

(1) Plate: thickness: 0.30 mm, width: 30 mm, component: Cu-30Zn

(2) Male terminal: thickness: 0.64 mm, width: 2.3 mm, component: Cu-30Zn

(3) Push-in type terminal: Press-fit terminal PCB connector, R800,manufactured by Tokiwa & Co., Inc.

(First Plating Conditions)

(1) Semi-Glossy Ni Plating

Surface treatment method: Electroplating

Plating solution: Ni sulfamate plating solution+saccharin

Plating temperature: 55° C.

Electric current density: 0.5 to 4 A/dm²

(2) Glossy Ni Plating

Surface treatment method: Electroplating

Plating solution: Ni sulfamate plating solution+saccharin+additives

Plating temperature: 55° C.

Electric current density: 0.5 to 4 A/dm²

(3) Cu Plating

Surface treatment method: Electroplating

Plating solution: Cu sulfate plating solution

Plating temperature: 30° C.

Electric current density: 0.5 to 4 A/dm²

(4) Matte Ni Plating

Surface treatment method: Electroplating

Plating solution: Ni sulfamate plating solution

Plating temperature: 55° C.

Electric current density: 0.5 to 4 A/dm²

(5) Ni-Plating

Surface treatment method: Electroplating

Plating solution: Ni sulfamate plating solution+phosphite

Plating temperature: 55° C.

Electric current density: 0.5 to 4 A/dm²

(Second Plating Conditions)

(1) Ag Plating

Surface treatment method: Electroplating

Plating solution: Ag cyanide plating solution

Plating temperature: 40° C.

Electric current density: 0.2 to 4 A/dm²

(2) Sn Plating

Surface treatment method: Electroplating

Plating solution: Sn methanesulfonate plating solution

Plating temperature: 40° C.

Electric current density: 0.5 to 4 A/dm²

(Third Plating Conditions)

(1) Sn Plating Conditions

Surface treatment method: Electroplating

Plating solution: Sn methanesulfonate plating solution

Plating temperature: 40° C.

Electric current density: 0.5 to 4 A/dm²

(Heat Treatment)

The heat treatment was performed by placing the sample on a hot plate,and verifying that the surface of the hot plate reached thepredetermined temperature.

(Post-Treatment)

For Examples 18 to 33, relative to Example 1, additionally a phosphoricacid ester-based solution was used as a surface treatment solution,application based on immersion or anode electrolysis (2 V,potentiostatic electrolysis) was performed, and thus the surfacetreatment of the plating surface was performed. The surface treatmentconditions in this case are shown in Table 2 presented below. Afterthese treatments, the samples were dried with warm air. For thedetermination of the amounts of P and N deposited on the platingsurface, first by using several samples having known deposition amounts,a quantitative analysis based on XPS (X-ray photoelectron analysismethod) was performed, and the detection intensities (number of countsdetected in 1 second) of P(2s orbital) and N(1s orbital) were measured.Next, on the basis of the thus obtained results, the relations betweenthe deposition amounts and the detection intensities were derived, andfrom these relations, the deposition amounts of P and N of unknownsamples were determined. FIG. 2 shows an example of the XPS analysisresults, and FIG. 3 shows the relations between the deposition amountsof the post-treatment solution components and the XPS detectionintensities (the unit of the deposition amount of P=1.1×10⁻⁹ mol/cm²;the unit of the deposition amount of N=7.8×10⁻¹¹ mol/cm²).

(Measurement of Thicknesses of Upper Layer, Intermediate Layer and LowerLayer, and Determination of Composition and Structure of Upper Layer)

The measurement of the thicknesses of the upper layer and theintermediate layer and the determination of the composition of the upperlayer of each of the obtained samples were performed by the lineanalysis based on the STEM (scanning transmission electron microscope)analysis. The analyzed elements are the elements in the compositions ofthe upper layer and the intermediate layer, and C, S and O. Theseelements are defined as the specified elements. On the basis of thetotal concentration of the specified elements defined as 100%, theconcentrations (at %) of the respective elements were analyzed. Thethickness corresponds to the distance determined from the line analysis(or area analysis). As the STEM apparatus, the JEM-2100F manufactured byJEOL Ltd. was used. The acceleration voltage of this apparatus is 200kV.

In the determination of the structure of the upper layer, the structurewas determined by comparing the composition determined on the basis ofSTEM with the phase diagram.

The thickness of the lower layer was measured with the X-ray fluorescentanalysis thickness meter (SEA5100, collimator: 0.1 mmΦ, manufactured bySeiko Instruments Inc.).

In the measurement of the thicknesses of the upper layer, theintermediate layer and the lower layer, and in the determination of thecomposition and the structure of the upper layer, the evaluations wereperformed for arbitrary 10 points and the resulting values wereaveraged.

(Evaluations)

For each of the samples, the following evaluations were performed.

A. Adhesive Wear

The adhesive wear was evaluated by performing an insertion/extractiontest for each of the plated male terminals according to Examples andComparative Examples by using a commercially available Sn reflow platingfemale terminal (090 type Sumitomo TS/Yazaki 09011 Series femaleterminal, non-waterproofing/F090-SMTS).

The measurement apparatus used in the test was the 1311NR manufacturedby Aikoh Engineering Co., Ltd., and the evaluation was performed with asliding distance of a male pin of 5 mm. The number of the samples wasset at five, and the adhesive wear was evaluated by using the insertionforce. As the insertion force, the averaged value of the maximum valuesof the respective samples was adopted. As the blank material of theadhesive wear, the sample of Comparative Example 11 was adopted.

The intended target of the adhesive wear is less than 85% of the maximuminsertion force of Comparative Example 11. This is because the insertionforce of Comparative Example 3 was 90% of the maximum insertion force ofComparative Example 11, and a larger reduction of the insertion forcethan the reduction of the insertion force in Comparative Example 3 wasadopted as the intended target.

B. Whiskers

Whiskers were evaluated by the load test (ball indenter method) of JEITARC-5241. Specifically, each of the samples was subjected to the loadtest, and each of the samples subjected to the load test was observedwith a SEM (model JSM-5410, manufactured by JEOL Ltd.) at amagnification of 100× to 10000×, and thus the occurrence state of thewhiskers was observed. The load test conditions are shown below.

Diameter of ball indenter: Φ 1 mm±0.1 mm

Test load: 2 N±0.2 N

Test time: 120 hours

Number of samples: 10

The intended property is such that no whiskers 20 μm or more in lengthoccurs, and the biggest intended target is such that no whiskers of anylength occurs.

C. Contact resistance

The contact resistance was measured with the contact simulator modelCRS-113-Au manufactured by Yamasaki-seiki Co., Ltd., under the conditionof the contact load of 50 kg, on the basis of the four-terminal method.The number of the samples was set at five, and the range from theminimum value to the maximum value of each of the samples was adopted.The intended target was the contact resistance of 10 mΩ or less.

D. Heat Resistance

The heat resistance was evaluated by measuring the contact resistance ofa sample after an atmospheric heating (200° C.×1000 h). The intendedproperty was the contact resistance of 10 mΩ or less, and the biggesttarget was such that the contact resistance was free from variation(equal) between before and after the heat resistance test.

E. Fine Sliding Wear Resistance

The fine sliding wear resistance was evaluated in terms of the relationbetween the number of the sliding operations and the contact resistanceby using the fine sliding tester model CRS-G2050 manufactured byYamasaki-seiki Co., Ltd., under the conditions of a sliding distance of0.5 mm, a sliding speed of 1 mm/s, a contact load of 1 N, and a numberof the back and forth sliding operations of 500. The number of thesamples was set at five, and the range from the minimum value to themaximum value of each of the samples was adopted. The intended propertywas such that the contact resistance was 100 mΩ or less at the time ofthe number of sliding operations of 100.

F. Solder Wettability

The solder wettability was evaluated for the samples after plating. Asolder checker (SAT-5000, manufactured by Rhesca Corp.) was used, acommercially available 25% rosin-methanol flux was used as a flux, andthe solder wetting time was measured by a meniscograph method. A solderSn-3Ag-0.5Cu (250° C.) was used. The number of the samples was set atfive, and the range from the minimum value to the maximum value of eachof the samples was adopted. The intended property was such that the zerocross time was 5 seconds (s) or less.

G. Gas Corrosion Resistance

The gas corrosion resistance was evaluated in the following testenvironment. The evaluation of the gas corrosion resistance was based onthe exterior appearance of each of the samples after the completion ofan environmental test. The intended property was such that the exteriorappearance is hardly discolored or somewhat discolored to a degreepractically causing no problem.

Hydrogen Sulfide Gas Corrosion Test

Hydrogen sulfide concentration: 10 ppm

Temperature: 40° C.

Humidity: 80% RH

Exposure time: 96 h

Number of samples: 5

H. Mechanical Durability

The mechanical durability was performed as follows. A push-in typeterminal was pushed into a through hole (board thickness: 2 mm, throughhole: Φ1 mm) and then extracted from the through hole, the cross sectionof the push-in type terminal was observed with a SEM (model JSM-5410,manufactured by JEOL Ltd.) at a magnification of 100× to 10000× and theoccurrence state of powder was examined. The case where the diameter ofthe powder was less than 5 μm was marked with “circle”, the case wherethe diameter of the powder was 5 μm or more and less than 10 μm wasmarked with “triangle”, and the case where the diameter of the powderwas 10 μm or more was marked with “X-mark”.

I. Bending Processability

The bending processability was evaluated by using a W-shaped mold on thebasis of the 90° bending under the condition that the ratio between theplate thickness of each of the samples and the bending radius was 1. Theevaluation was performed as follows: the surface of thebending-processed portion of each of the samples was observed with anoptical microscope, and the case where no cracks were observed andpractically no problems were determined to be involved was marked with“circle”, and the case where crack(s) was found was marked with“X-mark”. The case where “circle” and “X-mark” were hardlydistinguishable from each other was marked with “triangle”.

J. Vickers Hardness

The Vickers hardness of the lower layer was measured by pressing anindenter from the cross section of the lower layer of each of thesamples with a load of 980.7 mN (Hv 0.1) and a load retention time of 15seconds.

K. Indentation hardness

The indentation hardness of the upper layer was measured with ananoindentation hardness tester (ENT-2100, manufactured by Elionix Inc.)by pressing an indenter onto the surface of each of the samples with aload of 10 mN.

The indentation hardness of the lower layer was measured by pressing anindenter from the cross section of the lower layer of each of thesamples with a load of 10 mN (Hv 0.1) and a load retention time of 15seconds.

L. Surface Roughness

The measurement of the surface roughness (the arithmetic mean height(Ra) and the maximum height (Rz)) was performed according to JIS B 0601,by using a noncontact three-dimensional measurement apparatus (modelNH-3, manufactured by Mitaka Kohki Co., Ltd.). The cutoff was 0.25 mm,the measurement length was 1.50 mm, and the measurement was repeatedfive times for one sample.

M. Relation between Thickness of Upper Layer and Minimum Thickness ofUpper Layer

The relation between the thickness of the upper layer and the minimumthickness of the upper layer was evaluated by using a HAADF (high-angleannular dark-field) image based on the STEM (scanning transmissionelectron microscope) analysis. FIG. 4 shows a schematic diagram of theHAADF (high-angle annular dark-field). The evaluation was performed asfollows.

(1) In the evaluation, HAADF (high-angle annular dark-field) images at amagnification of 50 k were used, and the reference length of 3 μm/fieldof view was adopted.

(2) In the reference length of 3 μm/field of view, the minimum thicknesssite of the upper layer was identified. When the minimum thickness sitewas hardly identified, the site concerned was identified with amagnification, if necessary, elevated to a higher level.

(3) In order to precisely determine the minimum thickness of the upperlayer, the identified site was observed with a higher magnification. Byusing HAADF (high-angle annular dark-field) images at a magnification of100 to 200K, the “minimum thickness of the upper layer” was preciselydetermined.

(4) The relation between the above-described “thickness (μm) of theupper layer” determined by the line analysis based on the STEM (scanningtransmission electron microscope) analysis and the “minimum thickness(μm) of the upper layer” was grasped by measuring five fields of viewper one sample.

FIG. 4 schematically depicts the surface roughness of each of the layersas exaggerated than actual observation so as for the above-described (1)to (4) to be easily understood.

N. Relation Between Thickness of Upper Layer and Maximum Value ofElevation Differences Between Adjacent Hills and Valleys in Profile ofInterface Between Upper Layer and Intermediate Layer

The relation between the thickness of the upper layer and the maximumvalue of the elevation differences between the adjacent hills andvalleys in the profile of the interface between the upper layer and theintermediate layer was evaluated by using the HAADF (high-angle annulardark-field) image based on the STEM (scanning transmission electronmicroscope) analysis. FIG. 4 shows a schematic diagram of the HAADF(high-angle annular dark-field) image. The evaluation was performed asfollows.

(1) In the evaluation, HAADF (high-angle annular dark-field) images at amagnification of 50 k were used, and the reference length of 3 μm/fieldof view was adopted.

(2) In the reference length of 3 μm/field of view, the maximum valuesite of the elevation differences between the adjacent hills and valleysin the profile of the interface between the upper layer and theintermediate layer was identified. When the maximum value site of theelevation differences between the adjacent hills and valleys in theprofile of the interface between the upper layer and the intermediatelayer was hardly identified, the site concerned was identified with amagnification, if necessary, elevated to a higher level.

(3) In order to precisely determine the maximum value site of theelevation differences between the adjacent hills and valleys in theprofile of the interface between the upper layer and the intermediatelayer, the identified site was observed with a higher magnification. Byusing HAADF (high-angle annular dark-field) images at a magnification of100 to 200K, the “maximum value of the elevation differences between theadjacent hills and valleys in the profile of the interface between theupper layer and the intermediate layer” was precisely determined.

(4) The relation between the above-described “thickness (μm) of theupper layer” determined by the line analysis based on the STEM (scanningtransmission electron microscope) analysis and the “maximum value of theelevation differences between the adjacent hills and valleys in theprofile of the interface between the upper layer and the intermediatelayer” was grasped by measuring five fields of view per one sample.

FIG. 4 schematically depicts the surface roughness of each of the layersas exaggerated than actual observation so as for the above-described (1)to (4) to be easily understood.

The test conditions and the test results are shown in Tables 1 to 8. InTables 3, 6 and 7, the “composition” represents the ratio between therespective atomic concentrations (at %).

TABLE 1 First plating Second plating Third plating Heat treatmentconditions Thickness conditions Thickness conditions Thicknesstemperature Time No. [μm] No. [μm] No. [μm] [° C.] [sec] AtmosphereExamples 1 1 1 0.44 1 0.06 270 3 The air 2 1 1 1 0.28 1 0.02 270 3 Theair 3 1 1 1 0.52 1 0.08 270 3 The air 4 1 1 1 0.34 1 0.06 270 3 The air5 1 1 1 0.49 1 0.06 270 3 The air 6 1 0.07 1 0.44 1 0.06 270 3 The air 71 0.05 1 0.44 1 0.06 270 3 The air 8 1 3 1 0.44 1 0.06 270 3 The air 9 11 1 0.46 1 0.05 270 3 The air 10 1 1 1 0.43 1 0.08 270 3 The air 11 1 11 0.32 1 0.18 270 3 The air 12 2 1 1 0.44 1 0.06 270 3 The air 13 4 1 10.44 1 0.06 270 3 The air 14 1 1 1 0.44 1 0.06 270 3 The air 15 1 1 10.44 1 0.06 270 3 The air 16 3 1 1 0.44 1 0.06 270 3 The air 17 1 1 10.28 1 0.02 270 3 The air Reference 1 1 1 1 0.29 1 0.21 270 3 The airExamples 2 1 1 1 0.68 1 0.12 270 3 The air 3 1 1 1 0.07 1 0.01 240 3 Theair 4 1 1 1 0.5 1 0.04 270 3 The air 5 1 1 1 0.03 1 0.4 240 3 The air 65 1 1 0.44 1 0.06 270 3 The air 7 1 1 1 0.28 1 0.02 270 3 The air 8 1 11 0.28 1 0.02 270 3 The air 9 1 1 1 0.44 1 0.06 270 3 100% OxygenComparative 1 1 1 1 0.22 1 0.01 240 3 The air Examples 2 1 1 1 0.9 1 0.2270 15 The air 3 1 1 2 0.7 4 1 1 1 0.04 1 0.1 250 3 The air 5 1 1 1 0.061 0.84 270 3 The air 6 1 0.03 1 0.44 1 0.06 270 3 The air 7 1 5.5 1 0.441 0.06 270 3 The air 8 4 0.5 1 1 1 0.05 500 18 The air 9 4 0.5 1 0.5 10.06 280 3 The air 10 1 1 1 0.38 0.02 270 3 The air 11 4 1 2 0.9

TABLE 2 Conditions of treatment with phosphoric acid ester-basedsolution Cyclic Intensity ratio Phosphoric organic Deposition DepositionI(P2s)/I(N1s) acid ester compound amount of P amount of N between P andN No. species species mol/cm² mol/cm² detected by XPS Examples 18 A1 B11 × 10⁻⁹  8 × 10⁻¹¹ 1.13 19 A1 B1 3 × 10⁻⁹  9 × 10⁻¹¹ 1.82 20 A2 B1 2 ×10⁻⁹  8 × 10⁻¹¹ 1.40 21 A1 B2 2 × 10⁻⁹  9 × 10⁻¹¹ 1.83 22 A1 B3 2 ×10⁻⁹  8 × 10⁻¹¹ 1.29 23 A1 B3 1 × 10⁻¹² 8 × 10⁻¹¹ 0.06 24 A1 B1 1 ×10⁻¹¹ 8 × 10⁻¹¹ 0.13 25 A1 B1 4 × 10⁻⁸  8 × 10⁻¹¹ 10.67 26 A1 B1 7 ×10⁻¹⁰ 2 × 10⁻¹² 1.62 27 A1 B1 2 × 10⁻⁹  8 × 10⁻¹¹ 1.47 28 A1 B1 2 ×10⁻⁹  8 × 10⁻¹¹ 1.47 29 A1 B1 5 × 10⁻¹² 8 × 10⁻¹³ 1.00 30 A1 B1 8 ×10⁻⁸  4 × 10⁻⁸  3.49 31 A1 B1 9 × 10⁻⁷  8 × 10⁻¹¹ 53.40 32 A1 — 2 ×10⁻⁹  — ∞ 33 — B1 — 8 × 10⁻¹¹ 0 *) In relation to “Conditions oftreatment with phosphoric acid ester-based solution,” in Example 27,anode electrolysis was performed at 2 V for 5 seconds, and in Examplesother than Example 34, immersion treatment was performed. A1: Laurylacidic phosphoric acid monoester (phosphoric acid monolauryl ester) A2:Lauryl acidic phosphoric acid diester (phosphoric acid dilauryl ester)B1: Benzotriazole B2: Na salt of mercaptobenzothiazole B3: Tolyltriazole

TABLE 3 Thickness ratio Upper layer Intermedate layer between upperLower layer Thick- Thick- layer and Thick- ness Com- ness intermediateness Composition Structure [μm] position [μm] layer Structure [μm]Examples 1 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 Ni(semi-glossy) 1 2 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.10 Ag 0.20 1:2 Ni(semi-glossy) 1 3 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.40 Ag 0.20 2:1 Ni(semi-glossy) 1 4 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.10 3:1 Ni(semi-glossy) 1 5 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.25 55:45 Ni(semi-glossy) 1 6 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 Ni(semi-glossy) 0.07 7 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 Ni(semi-glossy) 0.5 8 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 Ni(semi-glossy) 3 9  Ag:Sn = 85:15 ξ-Phase 0.30 Ac 0.20 6:4 Ni(semi-glossy) 1 10 Ag:Sn = 3:1 ε-phase 0.30 Ag 0.20 6:4 Ni (semi-glossy)1 11 Ag:Sn = 4:6 ε-Phase + β-Sn phase 0.30 Ag 0.20 6:4 Ni (semi-glossy)1 12 Ag:Sn = 8:2 ε-phase 0.30 Ag 0.20 6:4 Ni (glossy) 1 13 Ag:Sn = 8:2ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 Ni (matte) 1 14 Ag;Sn = 8:2 ξ-Phase +ε-phase 0.30 Ag 0.20 6:4 Ni (semi-glossy) 1 15 Ag:Sn = 8:2 ξ-Phase +ε-phase 0.30 Ag 0.20 6:4 Ni (semi-glossy) 1 16 Ag:Sn = 8:2 ξ-Phase +ε-phase 0.30 Ag 0.20 6:4 Cu 1 17 Ag:Sn = 6:4 ε-Phase + β-Sn phase 0.05Ag 0.25 17:83 Ni (semi-glossy) 1 Reference 1 Ag:Sn = 3:7 ε-Phase + β-Snphase 0.30 Ag 0.20 6:4 Ni (semi-glossy) 1 Examples 2 Ag:Sn = 8:2ξ-Phase + ε-phase 0.60 Ag 0.20 3:1 Ni (semi-glossy) 1 3 Ag:Sn = 8:2ξ-Phase + ε-phase 0.05 Ag 0.03 63:37 Ni (semi-glossy) 1 4 Ag:Sn = 8:2ξ-Phase + ε-phase 0.20 Ag 0.4 1:2 Ni (semi-glossy) 1 5 Ag:Sn = 8:2ξ-Phase + ε-phase 0.03 Ag 0.40 7:93 Ni (semi-glossy) 1 6 Ag:Sn = 8:2ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 Ni:P = 98:2 1 7 Ag:Sn = 6:4 ε-Phase +β-Sn phase 0.05 Ag 0.25 17:83 Ni (semi-glossy) 1 8 Ag:Sn = 6:4 ε-Phase +β-Sn phase 0.05 Ag 0.25 17:83 Ni (semi-glossy) 1 9 Ag:Sn = 8:2 ξ-Phase +ε-phase 0.30 Ag 0.20 6:4 Ni (semi-glossy) 1 Comparative 1 Ag:Sn = 8:2ξ-Phase + ε-phase 0.03 Ag 0.20 13:87 Ni (semi-glossy) 1 Examples 2 Ag:Sn= 8:2 ξ-Phase + ε-phase 0.90 Ag 0.20 82:18 Ni (semi-glossy) 1 3 Sn β-Sn0.6 Ni (semi-glossy) 1 4 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.05 Ag 0.00591:9 Ni (semi-glossy) 1 5 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.60 1:2Ni (semi-glossy) 1 6 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 Ni(semi glossy) 0.03 7 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 Ni(semi-glossy) 5.5 8 Ag—Sn = 97:3 ε-Phase + β-Sn phase 0.9 Ni (matte) 0.59 Ag—Sn = 92:8 ε-Phase + β-Sn phase 0.45 Ni (matte) 0.5 10 Ag:Sn = 95:5α-Ag phase 0.30 Ag 0.20 6:4 Ni (semi-glossy) 1 11 Sn 0.8 Ni (matte) 1Intended 0.05 or 0.01 or 0.05 or target more and more and more and lessthan less than less than 0.80 0.50 5.00

TABLE 4 Whiskers Upper layer Lower layer Number of Number ofNanoindentation Surface roughness Vickers Nanoindentation whiskers lessthan whiskers of 20 μm hardness Ra Rz hardness hardness 20 μm in lengthor more in length [MPa] [μm] [μm] Hv [MPa] [pieces] [pieces] Examples 13850 0.22 2.35 300 3400 0 0 2 — — — — — 0 0 3 — — — — — 0 0 4 — — — — —0 0 5 — — — — — 0 0 6 — — — — — 0 0 7 — — — — — 0 0 8 — — — — — 0 0 9 —— — — — 0 0 10 — — — — — 0 0 11 — — — — — 0 0 12 6850 — — 600 6700 0 013 950 — — 130 1300 0 0 14 — 0.18 1.8 — — 0 0 15 — 0.13 1.2 — — 0 0 16 —— — — — 0 0 17 — — — — — 0 0 Reference 1 — — — — — ≤1 0 Examples 2 — — —— — 0 0 3 0 0 4 0 0 5 — — — — — 0 0 6 10800 — — 1200 12000 0 7 — — — — —0 0 8 — — — — — 0 0 9 — — — — — 0 0 Comparative 1 — — — — — — — Examples2 — — — — — — — 3 — — — — — — ≤2 4 — — — — — — — 5 — — — — — — — 6 — — —— — — — 7 — — — — — — — 8 — — — — — — — 9 — — — — — — — 10 — — — — — — —11 — — — — — — ≤3 Intended 0 target

TABLE 5 Adhesive wear Gas Insertion force Fine corrosion Maximuminsertion sliding resistance force/maximum Heat wear Solder Hydrogeninsertion force of resistance resistance wettability sulfide ComparativeContact Contact Contact Zero cross Exterior Example 11 resistanceresistance resistance time appearance Mechanical Bending [%] [mΩ] [mΩ][mΩ] [sec] after test durability processability Examples 1 Less than 801 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ ◯ 2 Less than 80 1 to 3 1to 3 10 to 50 2 to 4 Not discolored ◯ ◯ 3 Less than 80 1 to 3 1 to 3 10to 50 2 to 4 Not discolored ◯ ◯ 4 Less than 80 1 to 3 1 to 3 10 to 50 2to 4 Not discolored ◯ ◯ 5 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 6 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 7 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 8 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 9 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 10 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 11 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 12 Less than 80 1 to 3 1 to 3 10 to 50 1 to 3 Notdiscolored ◯ ◯ 13 Less than 80 1 to 3 2 to 4 10 to 50 2 to 4 Notdiscolored ◯ ◯ 14 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 15 Less than 80 1 to 3 1 to 3 10 to 50 1 to 3 Notdiscolored ◯ ◯ 16 Less than 80 1 to 3 1 to 3 10 to 50 2 to 4 Notdiscolored ◯ ◯ 17 Less than 80 1 to 3 1 to 3 10 to 50 1 to 3 Notdiscolored ◯ ◯ Reference 1 80 or more and 1 to 3 1 to 3  30 to 100 2 to4 Not discolored ◯ ◯ Examples less than 85 2 80 or more and 1 to 3 1 to3 10 to 50 2 to 4 Not discolored Δ ◯ less than 85 3 Less than 80 1 to 33 to 5  30 to 100 3 to 5 Somewhat ◯ ◯ discolored 4 80 or more and 1 to31 to 3 10 to 50 2 to 4 Not discolored Δ ◯ less than 85 5 80 or more and1 to 3 1 to 3 10 to 50 2 to 4 Somewhat Δ ◯ less than 85 discolored 6 631 to 3 1 to 3 10 to 50 2 to 4 Not discolored ◯ Δ 7 Less than 80 1 to 3 2to 4 10 to 50 2 to 4 Somewhat ◯ ◯ discolored 8 Less than 80 1 to 3 2 to4 10 to 50 2 to 4 Somewhat ◯ ◯ discolored 9 Less than 80 2 to 4 3 to 7 30 to 100 3 to 5 Not discolored ◯ ◯ Comparative 1 — — — — — Discolored— — Examples 2 85 or more — — — — — X — 3 90 — 10< 100< — — — — 4   —10< 100< 5< Discolored — — 5 85 or more — — — — — X — 6 85 or more — 10<— 5< — — — 7 — — — — — — X 8 — — — — — Discolored — — 9 — — — — —Discolored — — 10 — — — — — Discolored — — 11 100 — 10< 100< — — — —Intended less than 85 10 or less 10 or less 100 or less 5 or less Notdiscolored ◯ target Somewhat discolored (Discoloration practicallycausing no problem)

TABLE 6 Maximum value of elevation differences between Relation betweenadjacent thickness of Relation hills and upper layer and between valleysin maximum value of thickness profile of elevation differences Exteriorof upper interface between adjacent appearance Thickness layer betweenhills and valleys after gas ratio Minimum and upper in profile ofcorrosion between thickness minimum layer and interface betweenresistance Upper layer Intermediate layer upper and Lower layer of upperthickness intermediate upper layer and test with Thickness Thicknessintermediate Thickness layer of layer intermediate hydrogen CompositionStructure [μm] Composition [μm] layers Composition [μm] [μm] upper layer[μm] layer sulfide Examples 17 Ag:Sn = 6:4 ε-Phase + β-Sn phase 0.05 Ag0.25 17:83 Ni 1 0.04 Minimum 0.018 Maximum value of Not Plating at 1A/dm² Plating at 1 A/dm² (Semi- thickness elevation differencesdiscolored glossy) of upper between adjacent hills and layer ≥ valleysin profile of thickness interface between upper of upper layer andintermediate layer × 0.5 layer ≤ thickness of upper layer × 0.5Reference 7 Ag:Sn = 6:4 ε-Phase + β-Sn phase 0.05 Ag 0.25 17:83 Ni 10.02 Minimum 0.021 Maximum value of Somewhat Examples Plating at 4 A/dm²Plating at 1 A/dm² (semi- thickness elevation differences discoloredglossy) of upper between adjacent hills and layer < valleys in profileof thickness interface between upper of upper layer and intermediatelayer × 0.5 layer ≤ thickness of upper layer × 0.5 8 Ag:Sn = 6:4ε-Phase + β-Sn phase 0.05 Ag 0.25 17:83 Ni 1 0.03 Minimum 0.039 Maximumvalue of Somewhat Plating at 1 A/dm² Plating at 4 A/dm² (semi- thicknesselevation differences discolored glossy) of upper between adjacent hillsand layer ≥ valleys in profile of thickness interface between upper ofupper layer and intermediate layer × 0.5 layer > thickness of upperlayer × 0.5

TABLE 7 Surface of upper layer Region where atomic concentrationThickness (at %) of ratio Sn ≥ atomic Intermediate between concentration(at %) Heat Solder Upper layer layer upper of Ag and atomic resistancewettability Thick- Thick- and concentration (at %) Contact Contact Zerocross Com- ness Com- ness intermediate of O ≥10 at % resistanceresistance time position Structure [μm] position [μm] layers [μm] [mΩ][mΩ] [sec] Examples 1 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.20 6:40.0005 to 0.005 1 to 3 1 to 3 2 to 4 2 Ag:Sn = 8:2 ξ-Phase + ε-phase0.10 Ag 0.20 1:2 0.0005 to 0.005 1 to 3 1 to 3 2 to 4 3 Ag:Sn = 8:2ξ-Phase + ε-phase 0.40 Ag 0.20 2:1 0.0005 to 0.005 1 to 3 1 to 3 2 to 4Reference 9 Ag:Sn = 8:2 ξ-Phase + ε-phase 0.30 Ag 0.20 6:4 0.030 2 to 43 to 7 3 to 5 Examples

TABLE 8 Whiskers Adhesive wear Number Insertion force Gas Number of ofMaximum Fine corrosion whiskers whiskers insertion sliding resistanceless than of 20 force/maximum Heat wear Solder Hydrogen 20 μm μm orinsertion force of resistance resistance wettability sulfide in more inComparative Contact Contact Contact Zero Exterior Bending length lengthExample 11 resistance resistance resistance cross time appearanceMechanical process- [pieces] [pieces] [%] [mΩ] [mΩ] [mΩ] [sec] aftertest durability ability Examples 18 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 19 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 20 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 21 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 22 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 23 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 24 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 25 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 26 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 27 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 28 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 29 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 30 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 31 0 0 Less than 80 1 to 2 1 to 2 10 to30 0.5 to 2 Not discolored ◯ ◯ 32 0 0 Less than 80 1 to 2 1 to 3 10 to40   1 to 3 Not discolored ◯ ◯ 33 0 0 Less than 80 1 to 3 1 to 3 10 to50   2 to 4 Not discolored ◯ ◯ Intended 0 Less than 85 10 or less 10 orless 100 or less 5 or less Not discolored ◯ ◯ target

Examples 1 to 33 were each a metallic material for electronic componentsexcellent in any of the low degree of whisker formation, the lowadhesive wear property and the high durability.

In Reference Example 1, the ratio of Ag:Sn in the upper layer was 3:7,the proportion of Sn was somewhat larger, and hence the whiskers lessthan 20 μm in length occurred, and the adhesive wear property and thefine sliding wear resistance were poorer than those of Examples althoughthe intended properties were obtained.

In Reference Example 2, the thickness of the upper layer was 0.60 μm tobe somewhat thick, and hence the adhesive wear property and themechanical durability were poorer than those of Examples although theintended properties were obtained.

In Reference Example 3, the thickness of the intermediate layer was 0.03μm to be somewhat thin, and hence the heat resistance, the fine slidingwear resistance, the solder wettability and the gas corrosion resistancewere poorer than those of Examples although the intended properties wereobtained.

In Reference Example 4, the thickness of the intermediate layer was 0.4μm to be somewhat thick, and hence the adhesive wear property and themechanical durability were poorer than those of Examples although theintended properties were obtained.

In Reference Example 5, the thickness of the intermediate layer was 0.4μm to be somewhat thick, the ratio between the upper layer and theintermediate layer was such that upper layer:intermediate layer=7:93,thus the proportion of the intermediate layer was somewhat larger, andhence the adhesive wear property, the gas corrosion resistance and themechanical durability were poorer than those of Examples although theintended properties were obtained.

In Reference Example 6, the nanoindentation hardness of the upper layerwas 10800 MPa to be a somewhat large value, and hence the bendingprocessability was poorer than those of Examples although the intendedproperties were obtained.

In Reference Example 7, the minimum thickness of the outermost layer wasless than 50% of the thickness of the outermost layer, and the gascorrosion resistance was poorer than those of Examples although theintended properties were obtained.

In Reference Example 8, the maximum value of the elevation differencesbetween the adjacent hills and valleys in the profile of the interfacebetween the outermost layer and the upper layer exceeded 50% of thethickness of the outermost layer, and hence the gas corrosion resistancewas poorer than those of Examples although the intended properties wereobtained.

In Reference Example 9, on the surface of the upper layer, a regionwhere the total atomic concentration (at %) of the constituent elementsC≥2 the total atomic concentration (at %) of the constituent elements Band the atomic concentration (at %) of O≥10 at % was present in therange exceeding 0.02 μm, and hence the heat resistance and the solderwettability were poorer than those of Examples although the intendedproperties were obtained.

In Comparative Example 1, the thickness of the upper layer was 0.03 μmto be thinner than the intended target, and hence the gas corrosionresistance was poor.

In Comparative Example 2, the thickness of the upper layer was 0.90 μmto be thicker than the intended target, and hence the adhesive wearproperty and the mechanical durability were poor.

In Comparative Example 3, the upper layer was present as solely composedof n-Sn and was thicker than the intended target, and hence the whiskersless than 20 μm in length occurred, and the heat resistance and the finesliding wear resistance were poor.

In Comparative Example 4, the thickness of the intermediate layer was0.005 μm to be thinner than the intended target, and hence the heatresistance, the fine sliding wear resistance, the solder wettability andthe gas corrosion resistance were poor.

In Comparative Example 5, the thickness of the intermediate layer was0.6 μm to be thicker than the intended target, and hence the adhesivewear property and the mechanical durability were poor.

In Comparative Example 6, the thickness of the lower layer was 0.03 μmto be thinner than the intended target, and hence the adhesive wearproperty, the heat resistance and the solder wettability were poor.

In Comparative Example 7, the thickness of the lower layer was 5.5 μm tobe thicker than the intended target, and hence the bendingprocessability was poor.

In each of Comparative Examples 8 to 10, the proportion of Ag in theratio of Ag:Sn in the upper layer was as high as 90% or more, and hencethe gas corrosion resistance was poor.

Comparative Example 11 is the blank material.

FIG. 5 shows a schematic diagram of the results of the line analysis ofthe metallic material for electronic components according to anembodiment of the present invention with a STEM (scanning transmissionelectron microscope). In the case of FIG. 5, it is said thatsequentially from the outermost surface, the upper layer is formed of anAg—Sn alloy and is present in a thickness of 0.23 μm, and theintermediate layer is formed of Ag and is present with a thickness of0.15 μm. Moreover, the composition (at %) of the Ag—Sn alloy is alsosaid to be such that Ag:Sn=8:2. By comparing the ratio of Ag:Sn=8:2 withthe Ag—Sn phase diagram of FIG. 6, it is said that the ζ-phase (Sn: 11.8to 22.9%) and the ε-phase (Ag₃Sn) of the Sn—Ag alloy are present.

REFERENCE SIGNS LIST

-   10 Metallic material for electronic components-   11 Base material-   12 Lower layer-   13 Intermediate layer-   14 Upper layer

The invention claimed is:
 1. A metallic material for electroniccomponents, comprising: a base material; a lower layer formed on thebase material, the lower layer consisting of one or two or more selectedfrom a constituent element group A consisting of Ni, Cr, Mn, Fe and Co;an intermediate layer formed on the lower layer, without any interveninglayer, the intermediate layer consisting of one or two or more selectedfrom a constituent element group B consisting of Ag, Au, Pt, Rh, Os andIr; and an upper layer formed on the intermediate layer, the upper layerbeing constituted with an alloy consisting of one or two or moreselected from the constituent element group B consisting of Ag, Au, Pt,Rh, Os and Ir and one or two selected from a constituent element group Cconsisting of Sn and In, wherein the thickness of the lower layer is0.05 μm or more and less than 5.00 μm; the thickness of the intermediatelayer is 0.01 μm or more and less than 0.50 μm; and the thickness of theupper layer is 0.02 μm or more and less than 0.80 μm.
 2. The metallicmaterial for electronic components according to claim 1, wherein themaximum value (μm) of the elevation differences between adjacent hillsand valleys in a profile of an interface between the upper layer and theintermediate layer is 50% or less of the thickness (μm) of the upperlayer.
 3. The metallic material for electronic components according toclaim 1, wherein on the surface of the upper layer, a region where thetotal atomic concentration (at %) of the constituent elements C≥thetotal atomic concentration (at %) of the constituent elements B ispresent in the range of 0.02 μm or less on the surface of the upperlayer.
 4. The metallic material for electronic components according toclaim 1, wherein the upper layer comprises the metal(s) of theconstituent element group C in a content of 10 to 50 at %.
 5. Themetallic material for electronic components according to claim 1,wherein a ζ(zeta)-phase being a Sn—Ag alloy and/or an ε(epsilon)-phasebeing a Sn—Ag alloy is present.
 6. The metallic material for electroniccomponents according to claim 5, wherein a β-Sn being a Sn single phaseis further present.
 7. The metallic material for electronic componentsaccording to claim 1, wherein the thickness ratio between the upperlayer and the intermediate layer is such that upper layer:intermediatelayer=1:9 to 9:1.
 8. The metallic material for electronic componentsaccording to claim 1, wherein in the range from the upper layer to theintermediate layer, exclusive of the range of 0.03 μm from the outermostsurface of the upper layer, C, S and O are each included in a content of2 at % or less.
 9. The metallic material for electronic componentsaccording to claim 1, wherein the indentation hardness of the surface ofthe upper layer, the hardness being obtained by hitting a dent on thesurface of the upper layer with a load of 10 mN on the basis of ananoindentation hardness test, is 1000 MPa or more.
 10. The metallicmaterial for electronic components according to claim 1, wherein theindentation hardness measured from the surface of the upper layer, thehardness being obtained by hitting a dent on the surface of the upperlayer with a load of 10 mN on the basis of a nanoindentation hardnesstest, is 10000 MPa or less.
 11. A metallic material for electroniccomponents, comprising: a base material; a lower layer formed on thebase material, the lower layer comprising one or two or more selectedfrom a constituent element group A consisting of Ni, Cr, Mn, Fe and Co;an intermediate layer formed on the lower layer, without any interveninglayer, the intermediate layer consisting of one or two or more selectedfrom a constituent element group B consisting of Ag, Au, Pt, Rh, Os andIr; and an upper layer formed on the intermediate layer, the upper layerbeing constituted with an alloy consisting of one or two or moreselected from the constituent element group B consisting of Ag, Au, Pt,Rh, Os and Ir and one or two selected from a constituent element group Cconsisting of Sn and In, wherein the thickness of the lower layer is0.05 μm or more and less than 5.00 μm; the thickness of the intermediatelayer is 0.01 μm or more and less than 0.50 μm; and the thickness of theupper layer is 0.02 μm or more and less than 0.80 μm, and wherein thecontent of the metal(s) of the constituent element group A is 50% bymass or more in terms of the total content of Ni, Cr, Mn, Fe and Co inthe lower layer, and the rest of the alloy component of the lower layerconsists of one or two or more selected from the group consisting of B,P, Sn and Zn.
 12. A metallic material for electronic components,comprising: a base material; a lower layer formed on the base material,the lower layer consisting of one or two or more selected from aconstituent element group A consisting of Ni, Cr, Mn, Fe and Co; anintermediate layer formed on the lower layer, without any interveninglayer, the intermediate layer consisting of (i) one or two or moreselected from a constituent element group B consisting of Ag, Au, Pt,Rh, Os and Ir; and (ii) one or two or more selected from the groupconsisting of Bi, Cd, Co, Fe, In, Mn, Mo, Ni, Pb, Sb, Se, Sn, W, Tl andZn an upper layer formed on the intermediate layer, the upper layerbeing constituted with an alloy consisting of one or two or moreselected from the constituent element group B consisting of Ag, Au, Pt,Rh, Os and Ir and one or two selected from a constituent element group Cconsisting of Sn and In, wherein the thickness of the lower layer is0.05 μm or more and less than 5.00 μm; the thickness of the intermediatelayer is 0.01 μm or more and less than 0.50 μm; and the thickness of theupper layer is 0.02 μm or more and less than 0.80 μm, and wherein thecontent of the metal(s) of the constituent element group B is 50% bymass or more in terms of the total content of Ag, Au, Pt, Rh, Os and Irin the intermediate layer.
 13. A metallic material for electroniccomponents, comprising: a base material; a lower layer formed on thebase material, the lower layer consisting of one or two or more selectedfrom a constituent element group A consisting of Ni, Cr, Mn, Fe and Co;an intermediate layer formed on the lower layer, without any interveninglayer, the intermediate layer consisting of one or two or more selectedfrom a constituent element group B consisting of Ag, Au, Pt, Rh, Os andIr; and an upper layer formed on the intermediate layer, the upper layerbeing constituted with an alloy comprising one or two selected from aconstituent element group C consisting of Sn and In, wherein thethickness of the lower layer is 0.05 μm or more and less than 5.00 μm;the thickness of the intermediate layer is 0.01 μm or more and less than0.50 μm; and the thickness of the upper layer is 0.02 μm or more andless than 0.80 μm, and wherein the content of the metal(s) of theconstituent element group C is 50% by mass or more in terms of the totalcontent of Sn and In in the upper layer, and the rest of the alloycomponent in the upper layer consists of one or two or more selectedfrom the group consisting of Ag, As, Au, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo,Ni, Pb, Sb, W and Zn.
 14. The metallic material for electroniccomponents according to claim 1, wherein P is deposited on the surfaceof the upper layer, and the deposition amount of P is 1×10⁻¹¹ to 4×10⁻⁸mol/cm².
 15. The metallic material for electronic components accordingto claim 14, wherein N is further deposited on the surface of the upperlayer, and the deposition amount of N is 2×10⁻¹² to 8×10⁻⁹ mol/cm². 16.The metallic material for electronic components according to claim 15,wherein in the XPS analysis performed for the upper layer, with I(P2s)denoting the photoelectron detection intensity due to the 2S orbitalelectron of P to be detected and I(N1s) denoting the photoelectrondetection intensity due to the 1S orbital electron of N to be detected,a relation 0.1≤I(P2s)/I(N1s)≤1 is satisfied.
 17. The metallic materialfor electronic components according to claim 15, wherein in an XPSanalysis performed for the upper layer, with I(P2s) denotingphotoelectron detection intensity due to 2S orbital electron of P to bedetected and I(N1s) denoting the photoelectron detection intensity dueto 1S orbital electron of N to be detected, a relation1≤I(P2s)/I(N1s)≤50 is satisfied.
 18. A method for producing the metallicmaterial for electronic components according to claim 14, the metallicmaterial comprising: a base material; a lower layer formed on the basematerial, the lower layer consisting of one or two or more selected froma constituent element group A consisting of Ni, Cr, Mn, Fe and Co; anintermediate layer formed on the lower layer, without any interveninglayer, the intermediate layer consisting of one or two or more selectedfrom a constituent element group B consisting of Ag, Au, Pt, Rh, Os andIr; and an upper layer formed on the intermediate layer, the upper layerbeing constituted with an alloy consisting of one or two or moreselected from the constituent element group B consisting of Ag, Au, Pt,Rh, Os and Ir and one or two selected from a constituent element group Cconsisting of Sn and In, wherein the surface of the metallic material issurface-treated with a phosphoric acid ester-based solution including atleast one of the phosphoric acid esters represented by the followingformulas 1 and 2, and at least one selected from the group of the cyclicorganic compounds represented by the following formulas 3a, 3b, 3c, 3d,3e, 3f, 3g, 3h, 3i and 3j, and the formulas 4a, 4b, and 4c:

wherein, in formulas 1 and 2, R₁ and R₂ each represent a substitutedalkyl group and M represents a hydrogen atom or an alkali metal atom;

wherein, in formula 4a, R₁ represents a hydrogen atom, an alkyl group ora substituted alkyl group; R₂ represents an alkali metal atom, ahydrogen atom, an alkyl group or a substituted alkyl group; in formula4c, R₃ represents an alkali metal atom or a hydrogen atom; in formula4b, R₄ represents —SH, an alkyl group-substituted or arylgroup-substituted amino group, or represents an alkyl-substitutedimidazolylalkyl group; and R₅ and R₆ each represent —NH₂, —SH or —SM,wherein M represents an alkali metal atom.
 19. The method for producinga metallic material for electronic components according to claim 18,wherein the surface treatment with the phosphoric acid ester-basedsolution is performed by applying the phosphoric acid ester-basedsolution to the upper layer.
 20. The method for producing a metallicmaterial for electronic components according to claim 18, wherein thesurface treatment with the phosphoric acid ester-based solution isperformed by conducting an electrolysis by immersing the metallicmaterial after the formation of the upper layer in the phosphoric acidester-based solution and using as the anode the metallic material afterthe formation of the upper layer.
 21. An FFC terminal including acontact portion, using, in the contact portion thereof, the metallicmaterial for electronic components according to claim
 1. 22. An FPCterminal including a contact portion, using, in the contact portionthereof, the metallic material for electronic components according toclaim
 1. 23. An electronic component including an electrode, using, inthe electrode thereof for external connection, the metallic material forelectronic components according to claim
 1. 24. An electronic componentusing the metallic material for electronic components according to claim1, in a push-in type terminal thereof for fixing a board connectionportion to a board by pushing the board connection portion into athrough hole formed in the board, wherein a female terminal connectionportion and the board connection portion are provided respectively onone side and the other side of a mounting portion to be attached to ahousing.